body {
    height: 1600px;
    background-color: #f5f5f5;
}

h3 {
    width: 100%;
    text-align: center;
}

#node {
    background-color: #e9e9e9;
    width: 400px;
    height: 600px;
    margin: 0 auto;
    overflow-x: hidden;
    overflow-y: scroll;
}